Pompey left Spain to take care of itself, and remained in Rome, where he sought to add to his popularity by building a great stone theatre, large enough to hold forty thousand people, where for many days he amused the people with plays and games. Here, for the first time, a rhinoceros was shown. Eighteen elephants were killed by Libyan hunters, and five hundred lions were slain, while hosts of gladiators fought for life and honor.
While thus seeking popular favor, Pompey was secretly working against the interests of Cæsar, of whose fame he had grown jealous. His wife Julia died, and he joined his strength with that of the aristocrats; while Cæsar, a nephew of old Marius, was looked upon as a leader of the party of the people.
Pompey's power and influence over the senate increased until he was virtually dictator in Rome. Cæsar's ten years' governorship in Gaul would expire on the 1st of January, 49 B.C., and it was resolved by Pompey and the senate to deprive him of the command of the army. But Cæsar was not the man to be dealt with in this summary manner. His career of conquest ended, he entered his province of Cisalpine Gaul, or Northern Italy, where he was received as a great hero and conqueror. From here he sent secret agents to Rome, bribed with large sums a number of important persons, and took other steps to guard his interests.
Meanwhile the senate tried to disarm Cæsar by unfair means. They had the power to shorten or lengthen the year as they pleased, and announced that that year would end on November 12, and that Cæsar must resign his authority on the 13th. Curio, a tribune of Rome and Cæsar's agent, said that it was only fair that Pompey also should give up the command of the army which he had near Rome. This he refused to do, and Curio publicly declared that he was trying to make himself a tyrant.
Finally the senate decreed that each general should give up one legion, to be used in a war with the Parthians. There was no such war, but it was pretended that there soon would be. Pompey agreed, but he called upon Cæsar to send him back a legion which he had lent him three years before. Cæsar did not hesitate to do so: he sent Pompey's legion and his own; but he took care to win the soldiers by giving each a valuable present as he went away. These legions were not sent to Asia, but to Capua. The senate wanted them for use nearer than Parthia.
Cæsar was then at Ravenna, a sea-side city on the southern limit of his province. South of it flowed a little stream called the Rubicon, which formed his border-line. Here he took a bold step. He sent a letter to the senate, offering to give up his command if Pompey would do the same. A violent debate followed in the senate, and a decree was passed that unless Cæsar laid down his command by a certain day he should be declared an outlaw and enemy of Rome. At the same time the two consuls were made dictators, and the two tribunes who favored Cæsar—one of them the afterwards famous Marc Antony—fled for safety from Rome.
The decree of the senate was equivalent to a declaration of war. On the one side was Pompey, proud, over-confident, and unprepared. On the other was Cæsar, knowing his strength, satisfied in the power of the money he had so freely distributed, and sure of his men. He called his soldiers together and asked if they would support him. They answered that they would follow wherever he led. At once he marched for the Rubicon, the limit of his province, to cross which stream meant an invasion of Italy and civil war.
Plutarch tells us that he halted here and deeply meditated, troubled by the thought that to cross that stream meant the death of thousands of his countrymen. After a period of such meditation, he cried aloud, "The die is cast; let us go where the gods and the injustice of our foes direct!" and, spurring his horse forward, he plunged into the stream.
This story, which has been effectively used by a great epic poet of Rome, probably relates what never happened. From all we know of Cæsar, the question of bloodshed in attaining the aims of his ambition did not greatly trouble his mind. Yet the story has taken hold, and "to cross the Rubicon" has become a proverb, signifying the taking of a step of momentous importance.
Cæsar, after the legions sent the senate, had but a single legion left with him. He sent orders to others to join him with all haste, but they were distant. As for Pompey, knowing and despising the weakness of his rival, he had made no preparations. He had Cæsar's two legions at Capua and one of his own at Rome, while thousands of Sulla's veterans were settled in the country round. "I have but to stamp my foot," he said, "and armed men will start from the soil of Italy."